Certain mailing machines including certain DM SERIES mailing machines available from Pitney Bowes Inc. of Stamford, Conn. include an envelope flap sealing subsystem. The envelope flap sealing subsystem includes a gravity-fed fluid delivery subsystem that feeds an appropriate moistening fluid to a wick and then brush that moistens an envelope flap as the envelope is fed past the flap sealing subsystem.
The fluid delivery subsystem includes a moistening fluid storage bottle that holds a supply of moistening liquid that is gravity-fed in a “chicken-feeder” fashion to the wick and brush combination that applies the moistening fluid to the flap of an envelope. The moistening fluid storage bottle has a cap that incorporates a spring-loaded plunger to seal it from leaking when the bottle is in the cap-down orientation needed to install or withdraw it from the moistener. There is a post-like feature in the moistener that pushes the spring loaded plunger to the open position as the bottle completes its engagement in the moistener fluid tray. Since the spring force on the plunger is higher than the weight of the empty bottle, it will cause the bottle to rise vertically was it nears being empty. In such a system the operator will not know when it is advisable to replace the moistening fluid bottle. If an operator wishes to start a large envelope batch job, it may be necessary to know if a suitable amount of moistening fluid is available before starting the batch job.
Certain prior mailing machines including envelope moistening subsystems included either a sight glass in the wick tank or a float that activated an optical sensor. Both prior systems only indicate when there is no liquid remaining in the bottle and are not as useful for providing a preventive maintenance indication that an almost empty bottle should be changed to accommodate a large batch mail run. Moreover, they may not indicate a missing fluid container.
Accordingly, there is a need for an inexpensive mechanism for indicating moistener fluid level status or to indicate a missing fluid container. Optical detectors are sometimes used to detect fluid levels, but they require wiring in close proximity to the moistening liquid that could damage the detector and/or the printed circuit board that is driving it. Certain optical detectors require floats that can stick to walls due to the surface tension of the moistening liquid or containers having transparent walls that may get dirty over time. This illustrative embodiments of the present application fulfill at least the need for indicating to the operator that the moistener liquid level is getting low, when it is depleted and/or an indication of the number of envelopes that may be moistened.